Beat together the butter, sugar, honey and lemon zest until creamy. Beat in the egg yolks one at a time.
Into a separate bowl, sift the flour, baking powder, baking soda and pinch of salt. Fold in the batter, alternating with the yoghurt. Fold in the sultanas and cardamom seeds. Beat the egg whites until stiff and fold carefully into the mixture.
Pour into a greased tin,
To make the syrup, boil the syrup ingredients together for 5 minutes, stirring to combine. Pour the cooled syrup carefully over the hot cake or pour warm syrup over the cake once it is completely cooled.